Sensors are important for performing various types of operations, e.g. by movable or stationary objects. Especially, movable objects, such as robots, manned vehicles and unmanned vehicles, can take advantage of different sensors for navigating in a complex environment. For example, movable objects need to be aware of surrounding condition in order for performing path planning and obstacle detection and avoidance in an unknown environment. This is the general area that embodiments of the invention are intended to address.